Silicon carbide (SiC) has characteristics that are not seen in silicon (Si). Compared with Si, SiC has a band gap of about 2-3 times wider, a breakdown voltage of about 10 times higher, and a heat conductivity of about 10 times higher. Taking advantage of these characteristics, in recent years, the SiC semiconductor device including the SiC single crystal is expected to be utilized in applications such as a power device which overcomes the physical limitation of the Si semiconductor device including Si or an environment-resistant device which operates at a high temperature.
An example of a method of manufacturing such an SiC semiconductor device is disclosed, for example, in Patent Document 1 (Japanese Patent Laying-Open No. 2001-68428). Hereafter, with reference to FIGS. 14-18, the example of the method of manufacturing the SiC semiconductor device disclosed in Patent Document 1 will be described.
First of all, an epitaxial layer 102 composed of an n type 4H—SiC single crystal is grown epitaxially on an underlying layer 101 which is an 8° off-axis (0001) Si plane composed of an n type 4H—SiC single crystal, and then an oxide film 103 is formed by pyrogenic oxidation on epitaxial layer 102, as shown in the schematic cross sectional view in FIG. 14.
Then, after forming a patterned photoresist film 104 on the surface of oxide film 103, as shown in the schematic cross sectional view in FIG. 15, oxide film 103 exposed through photoresist film 104 is removed by buffered hydrofluoric acid to expose the surface of epitaxial layer 102.
Subsequently, as shown in the schematic cross sectional view in FIG. 16, ion implantation of boron ion 105 is performed at a room temperature on the surface of exposed epitaxial layer 102, to form an impurity region 107 in the surface of epitaxial layer 102.
Then, photoresist film 104 is removed by O2 plasma ashing and oxide film 103 is completely removed by buffered hydrofluoric acid. As shown in the schematic cross sectional view in FIG. 17, a diamond-like carbon film 106 with a thickness of about 100 nm is then formed on the surface of epitaxial layer 102 by an ECR-CVD method using methane.
Annealing is then performed for 30 minutes at 1700° C. in an argon atmosphere to activate the ion-implanted boron.
As shown in the schematic cross sectional view in FIG. 18, diamond-like carbon film 106 is then removed by O2 plasma ashing.
According to the method of manufacturing the SiC semiconductor device of Patent Document 1, the surface roughness caused by step bunching on the surface of epitaxial layer 102, after removal of diamond-like carbon film 106, can be suppressed.    Patent Document 1: Japanese Patent Laying-Open No. 2001-68428